On Tue, 12 Mar 2002, Nick Gemas wrote:
> I have a 74 TR6. Anyone have any head flow numbers for the late head? I'm
> particularly interested in the stock flow numbers as well as any modified head
> flow numbers.
> Thanks
> Nick
Nick,
By pure chance, I am looking for the same numbers. So far - nothing. If
you do get anything, I would be most appreciative if you were to share
them with the list.
What I do know is that the later head flows better out of the box, what I
don't know are any bench flow numbers.
Bottom line - if you wanna make power, you play with the head. Warning,
hogging out the head can possibly cause the flow to reduce in some cases,
so don't go hogging out your ports without any knowledge of what you are
doing. This is why some folks charge $$$$ for head work. There's the black
art portion of the equation and there's the practial knowledge part of the
equation. As an example of "practical knowledge" - you need to know why
"circle B" heads are more suited to porting/milling than other heads that
are available. I can't explain the black art part, you need detailed
knowledge of fluid dynamics, or a good "sense" of what works or not.
Having said that, if you merely port-match your head to your manifolds and
use a high quality extractor-type exhaust system, you will get more "bang
for the buck" than you would get by a wild porting job. Further, the
"tractability" of the motor will be more suited to street driving with the
port-match/good header.
By way of dollar comparison, most anyone can port match, but a machinist
should be able to match your ports for under 2 hours labor. Figure $100
for that. Then spend $400 on a header and another $200-300 for a good,
proper exhaust system. You're in the $700-$800 range. And even with a
stock cam etc, you should be able to squeak 20 or so HP out of your stock
engine. Go to a person that knows heads and have them do all the trick
stuff to your TR6 head, and you'll have to part with $1200 or so, AND you
can't take advantage of it without the extractor exhaust system above.
If your intent is to play with the cam, then you need to keep other
factors in mind including compression ratio... but the last thing you do
is hog the head out so as to get the last few "ponies" out of the setup.
That's enough for now.
rml
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